Virtually all electronic devices are susceptible to transient perturbations such as electrostatic discharge or electromagnetically coupled interference. The perturbations often occur at the Input/Output (I/O) interfaces to the electronic devices. Typical examples of I/O interfaces susceptible to the transient perturbations, or signals, are power supply input terminals and data bus terminals to name only a few.
TVS junction diodes have typically been used to protect electronic devices from damage caused by transient voltage signals. TVS junction diodes placed into electronic devices for transient suppression are reverse biased under normal, non-transient conditions. During transient conditions, however, the reverse bias voltage exceeds the reverse breakdown voltage and the TVS junction diode clamps the transient voltage to be equal to the reverse breakdown voltage of the diode, thereby preventing the transient voltage from exceeding the maximum voltage that can be sustained by the electronic device.
Prior art TVS junction diodes perform well for high voltage (e.g., >5 volt) applications, but pose specific detrimental characteristics in low voltage (e.g., <5 volt) applications. The detrimental characteristics of low voltage TVS junction diodes include high breakdown voltages. Electronic devices today are designed to operate at battery supplied potentials below 5 volts, such as 3 volts and 1.8 volts or even lower. The current requirements of the battery operated circuits are being driven lower as well. Since the maximum voltage that many of these electronic devices can withstand is relatively low, it would be desirable to reduce the breakdown voltage so that the TVS junction diode clamps the transient voltage at lower levels.